Holddown mechanism for shearing machines



y 1929- F.. E. MUNSCHAUER HOLDDOWN MECHANISM FOR SHEARING MACHINES Filed Feb. 4, 1924 4 Sheets-Sheet 1 I j/vvavroze HTTYS.

y 1929- F. E. MUNSCHAUER ,7

v HOLDDOWN MECHANISM FOR SHEARING MACHINES Filed Feb. 4, 1924 4 Sheets-Sheet 2 y 30, F. E. MUNSCHAUER HOLDDOWN MECHANISM FOR SHEARING MACHINES Filed Feb. 4, 1924 Sheets-Sheet July 30, 1929.

F. E. MUNSCHAUER HOLDDOWN MECHANISM FOR SHEARING MACHINES 4 Sheets-Shet 4 Filed Feb. 4, 1924 & 6 M A Patented July 30, 1929.

UNITED STATES PATENT OFF ICE.

FREDERICK E. MUNSCHAL'UER, OF BUFFALO, NEW YORK, ASSIGNOB. 1'0 1m- I CHINE AND TOOL WORKS, OF BUFFALO, NEW- YORK, A. CORPORATION 01' YORK.

HOLDDOWN MECHANISM FOR SHEABING MACHINES.

NEW

Application flied February 4, 1924. Serial No. 690,372.

This invention relates to a holddown mechanism for shearing machines.

In holddown mechanisms for this purpose as heretofore constructed it has been impossible to always maintain the same grip or hold upon the sheet throughout the width thereof, this being due to the fact that the holddown mechanism would not always bear evenly upon the sheet along that portion which was being out, with the result that the sheet would oflten slip out of place and not be cut proper lit is the object of this invention to provide 'a holddown mechanism for shearing machines which will always hear uniformly against the sheet or material throughout the width there of and hold the same reliably in place during the shearing or cutting operation regardless of any unevenness in the thickness of the material and thereby permit of alwayscutting the sheets perfectly and along, the line it was intended to be cut.

In the accompanying drawings:

Figure 1 is a front elevation of a shearing machine having an under-drive and equipped with my improved holddown mechanism, and showing the latter in its depressed or operative position.

Figure 2 is an end elevation thereof.

Figure 3 is a fragmentary front elevation of the same showing the holddown mechanism elevated or in its inoperative position.

Figure 4 is a fragmentary vertical longitu-- dinal section taken on line 44, Figure 3.

Figure 5 is a fragmentary horizontal section taken on line 5-5, Figure 1.

Figure 6 is a fragmentary front elevation of a shearing machine having an overhead drive and equipped with a modified form of -my holddown mechanism.

Figure 7 is a fragmentary vertical longitudinal section, taken on line 7-7, Figure 6.

Figures 8 and 9 are fragmentary vertical longitudinal sections showing other variations in detail of construction of the holddown mechanism containing my invention.

- Referring to the machine illustrated in Figures 1 to 5, the numeral 10 represents the bed or table of the shearing machine which is supported at its opposite ends upon standards or legs 11, 12 and provided on its rear side with a lower knife 13 which is arranged transversely. and has its upper edge arran ed flush with the top of the bed, as shown in igure' 4. I

Arranged transversel above the bed is a vertlcally movable cross ead 14 which is guided at its opposite ends in vertical ways 15 on the upper parts of the standards and provided on its front side with an upper knife 16 which is adapted to cooperate with the lower knife 13 for the purpose of shearing the plate or sheet of metal 17 which is supported upon the bed and projects across the cutting line between may be raised and lowered by any suitable and Well-known means, those shown in the drawings being well-known and approved and comprising a main shaft 18 arranged horizontally and transverselybelow the bed and journaled at its opposite ends in bearings 19 and 20 on the lower dparts of the standards, at opposite-ends of the cranks 21, 21 mounte main shaft outside of the standards, and connecting rods 22, 22 which are pivotally connected at their lower ends with the cranks 21,

while their upper'ends are pivotally connect; ed with opposite ends of the cross head by means of the pins 23. Due to this construction the cross head 'will be raised and lowered during each rotation of the main shaft 18 and produce a cutting operation of the machine.

The main shaft may be driven in various ways, for instance, by means of a drivin shaft 24 journaled in a bearing 25 on one o the standards and an out-bearin 26 arranged on the pedestal 27 and provided at its inner end with a gear pinion 28 which meshes with the gear wheel 29 on the main shaft and also provided adjacent to the pedestal 27 with a pulley 30 adapted to rece ve a belt whereby power is transmitted to the machine from any suitable source.

the upper and lower knives. This cross head a The form of holddown mechanism shown in I Figures 1 to 5 which embodies my invention is constructed as follows Arranged transversely in front of the cross head 14 is a horizontal holddown bar which is preferably constructed of U-shaped form in cross section and has a vertical'web 31 and upper and lower flanges 32, 33 which pro'ect rearwardly from the upper and lower e "es of this web. This holddown bar is guided on the standards so as to be capable of moving vertically thereon toward and from the bed, this being preferabl effected by means of guide blocks 34 secure to op osite ends of the holddown bar and guide bo ts 35 passin through vertical slots 36 in the outer edges 0 the guide blocks 34 and engaging their rear threaded ends with the adjacent parts of the standards while the heads 37 at their front ends-engage with the-front sides of the guide blocks34, as shown in Figures 1 and 5. The vertical movement of the holddown bar and the parts associated therewith is preferably imparted thereto by motion derived from the main shaft 18 for which purpose an inter mediate actuating mechanism is provided which in the exam le shown in the Figures 1 to '5 is construct as follows: 1

Arranged adjacent to opposite ends of the holddown bar and above the latter are two intermediate levers each of which is of L- shaped or bell-crank form and each fulcrumedon a fixed center by means of a longitudinal horizontal pin 38 and having an upper horizontal arm 39 which projects laterally outward from this fulcrum and a vertical 7 lower arm 40 which depends from this fulcrum, a link 41 connecting the lower end of i the vertical arm 40 of each'intermediate lever with the upper end of the. guide block on the adjacent end of the holddown bar, two elbow levers 42 pivotally mounted by means of horizontal transverse pins 43 on the'outer sides of the lower parts of the standards so that each elbow lever with the upper horizontal each is capable of swinging in a vertical plane, a connecting rod 44 connecting one arm of arm 39 of the intermediate lever on the same arm of the adjacent elbow lever. QIhe nu-v side of the machine, and two cams 45 arranged on opposite ends of the main shaft 18 and each engaging with a roller 46 on the other meral 47 represents two vertical guide rods arranged in front of theupper parts of the standards and each pivotally connectedat its upperend withthe horizontal arm of the adjacentintermediate lever while its lower end is guidedin a lug 48 on the adjacent part I of the respective standard. Each of these ide. rods is surrounded by'a spring 49 which ears at its lower end against the guide lug 48 m1 at its upper end against the underside of the respective horizontal arm 39.

' x will During each rotation of the main shaft 18 the cams 45 by engaging their high surfaces with the rollers 46 of the elbow levers cause the latter to be turned in a direction which produce a positive downwardvmot'ion of the holddown bar'31, 32, 33 toward the bed of the machine, this being caused by the two intermediate levers at this time turning in a direction which will cause the lower arms 40 of these levers'and t e links41 to be straight ened'in the form 0 a toggle, asshown in Figure 1 and thereby produce alpowerful the low faces of t e cams 45 are n the holddown bar.

lowering effect u resented to v the rollers 46 of the elbow levers, t e resilience of the springs 49 operate to turn the intermediate leversin the opposite direction so as to cause the lower arms 40 of these levers and nut is the links 41 between the same and the holddown bar to be folded with a toggle action, as

' in the form of apin having a lower enlarged art 50 and an upper reduced part 51 thereby orming an upwardly facing shoulder 52 between the enlarged lower and the reduced upper part of this pin.- The lower and upper flanges of the holddown bar are provided with a plurality of pairs of guide openings, the loweropenmg 53'and the upper opening 54 of each pair being arranged'vertically in line, and the respective lower opening being comparatively large and receiving the enlarged lower part 50 of the retaining pin and the companion upper opening 54 receiving.

the reduced upper part of the same retaining p n tairiing pins is projected with its lower end yleldingly below the lower end of the holddown bar, this being preferably accomplished 4 by means of a spring .55 surrounding the upper reduced part 51 of the retaining pin and- .bearing at its lower end against the'shoulder 52 of this pin while. its upper end bears against the underside of the upper-flange 32 of the holddown bar, as shown in Figure 4.

as shown in Figure 4'. Each of the re- The downward movement-of each retaining pin is limited by a stop device which is preferably capable of adjustment so as to be capable of varying the position of the lower-end of the retaining pin relatively to the holddown bar in the pro'ected position of this pin.

In the prefer-rd construction this stop llO device consists of a screw nut-.56 which is arranged on the upper screw threaded end of the reduced part of the retaining pin and adapted'to engage with the upper side of the upper flange of the holddown bar. This stop means of a clamping nut 57 applied to the reduced part of this retaining pin and en gaging with the upper side of the adjusting nut 56. a

In the operation of the machine the cross head-and the holddown bar are both elevated held in place after adjustment by' while the attendant is pushing or feeding a the sheet' of metal forwardly into the posi- As tion in-which it is to betcut. Thereafter the holding bar is moved downwardly and during the first part of this downwardmovement the lower ends of the retaining pins engage with the upper sidev of the sheet which is to be cut, at-difierent points .inthe width thereof, andduring the final'part of the downward movement of the holding bar the same moves independently of the retaining pins so that the tension on the springs 55 which are applied to these pins is increased. During this downward movement of the holddown bar the retaining pins engage with the sheet independently of each other which permits each pin as it comes in contact with-the sheet to be arrested thereby and permit the other retaining pins to subsequently also engage'with the respective parts of the sheet and be arrested thereby in-. dependently of each other until all of the several pins are thus engaged with the sheet. It follows from this construction that all parts of the sheet are thus firmly engaged by" the several pins regardless of any irregularity or variation in the thickness of the sheet throughout thewidth thereof and also regardless of whether or not the lower ends of the several pins are horizontally in line and equidistant from the bed when the holddown baris in its elevated or retracted position. As a result of this organizaiton and operation the sheet will be firmly and re 'liably gripped throughout its widthand; held in place on the bed so that during the subse quent operation of cutting the sheet by reason of the downward movement of the cross head which follows the descent of the holddown barand causes the sheet to be severed between the lower fixed and upper movable knives and produce a cut of the sheet which is absolutely perfect and in accord with the j line on which it was intended to sever the same. l

. After the sheet has been cut by the shearing knivesthe cross head is first moved so as to raisethe upper, knife out of the path of the sheet and then the holddown bar is raised-for the purpose of disengaging the lower ends of the retaining pins from the sheet and permittingthe latter to be advancedfor cutting the sameat anotherplace or enabling the sameto be replaced by another sheet to be ,cutL During such upward 7 movement of the holddown bar, the same I moves idlyduringthe first part of this move mentiindependently of the retaining pins until the upper side of the flange 32 of this vbar engageswith thefstop'nuts 56 of the sevvl eral retaining pins and thereafter during the I. f last part of the upward movementnof this bar the several retaining pins are carried I v pQintS of'its width against the hed in the Same mannenpreviously described in the explanaupwardly therewith i'iito'their uppermost or i fully retracted positiong, Byturning the stop "screw nuts, 56 on the upperends of the sev- I eral retaining pins} the latter maybe adjusted; vertically on'thel iolddown' b r-Sp; as to adapt the lower ends of these pins 'tojv the' upper ends of the standards, motion being transmitted from this shaft to this cross head by means which comprise an eccentric 61 arranged on the shaft 58 and surrounded by an eccentric strap '62 which is connected by means of a rod 63 with a pivot 64 on the adjacent end'of the cross head 59, and power being applied to this shaft bymeans of a belt passing around a pulley 99 on one end thereof. 1 i

In this modified form of my improved holddown mechanism for overhead driven shears mechanism employed for raising'the holddown bar is constructed as follows:

The numeral 65 represents an intermediate rock lever which is pivoted at its rear end by means of a pin 66 on a cross bar 67 arranged on. the upper ends of the standards, a link 68 connecting the front end/of the intermediate lever with the upper side of the holddown bar 31, an upper actuating lever preferably of elbow form pivoted by means of a pin 69 to the upper part of the cross bar 67 and having its front arm 70 connected by means of a link 71 with the intermediate lever 65 and having'its rear arm 72 constantly pressed downwardly by means of the spring 7 3 which is interposed between the upper side of the arm 72 and a screw nut 7 4 which is connected by means of a rod 75 with the cross bar 67,

results in a folding action of this front arm 70 and the link 71 in the form'ofa toggle, whereby the holddown bar 31 is elevated together with its retaining pins into an in0perative or retracted position. As'the shaft 58 rotates andengages the high face of thecam 76 withithe roller 77, then the link 71 and the frontai'm, 70 of the actuating lever are 1 straightened in the form of, a toggle whereby the spring 73 is compressed and the intermedizrteFlevjerv 65 is swung downwardly so that l lddown' barftogether withits-retaining operation cram in the sheet atdifferent 'shearing on thesheet;

tion of to 5" prior to. effecting the vention,

an 'ever'head shaft fre by 'ineans of 5a, Lpin 8:1

mojyed' downwardly for effecting the i i 5-1 'shiiwnf" in Figu es,- t-h'e holddown-"bar;31 i I is r'a ediand lowered hy-m'otionderived from n on fan overhead bracket 82 forming- 'partidf the main frame; a'link 8 3 connecting the low- I against a washer 90 which on the upper part of the tension rod 86 by a toggle and thereby cause the holddown bar er arm of the lever with the upper part of the holddown bar,- a cam 84 arranged on t e shaft 79 and operating upon a roller 85 arranged on the upper arm of the lever 80, a tension rod 86 pivotally connected at its lower end by means of a pin 87 with the link 83, whileits central part slides through a guide lug 88 on the central part of the lever 80 and a spring 89 surrounding the upper part of the tension rod 86 and bearing with its lower end against the guide lug 88 and at its upper end is held in place means of a screw nut 91 thereon.

In this construction the high part of the face of the cam 84 operates to depress the arm of the lever 80 which carries the roller 85 and thereby the direction in which it will produce a straightening effect of the same. inrelation to the link 83, in the manner of thereby causes the holddown bar 31 to be low ered. As the low face of the cam 8 k is presented to the roller 85 of the lever 80 the resilience of the spring 89 will cause the link 83 and the lever 80 to be turned rearwardly into a folded pos1t1on similar to the action of 31 together with the retaining pins mounted thereon to be elevated and thus clear the path above the bed or the table for releasing the sheet resting thereonpreparatory to forming another cutting operation.

Instead of arranging this spring mechanism in an overhead driven machine for raising the holddown bar in front of the main shaft 79, this spring mechanism may be arranged in rear of this shaft as shown in Figure 9. In such a construction the tension rod 92 is pivotally connected at its lower end with the rear arm 93 of .the elbow lever 80 and guided with its central part in 9. lug 94 on the overhead bracket 82 of the main frame and a spring 95 surrounds the upper part of thetension 'rod' and' bears at its lower end against the lug 94, while its upper end bears against a washer or shoulder 96 which is held in place on the upper end of the tensionrod 92 by means of screw nuts 97 applied to this end of the rod.

In the several constructions herein shown.

embodying my improved holddown} mechanism the holddown bar is raised and lowered by a toggle action which is straightened by means of cams for the purpose of producing a powerful pressure upon the retaining pins whereby reliably held in place and the foldingof the toggle members is effected by means .of a return spring, thereby furnishing an apparatus for this purpose which is comparatively simple in construction and capable of beng operated with a minimum amount of jpower, while at the same time enabling a I rm and reliable hold or grip to be obtained carries the other arm of this lever in a toggle, and

said holddown bar same engages the material being cut.

the sheet of metal to be out isupon the sheet which is to be out, which will tion the main part of the load for doing this i work is taken up by this toggle mechanism with'comparative ease and thus relieves the holddown cams from undue wear while this work is performed.

I claim as my invention:

1. A shearing machine comprising a bed adapted to support a holddown mechanism having a bar mov able toward and from said material, and means for actuating said-bar comprising two upper levers each having a lateral projecting arm and a downwardly projecting toggle arm, twotoggle links each connecting one of said toggle arms with one end of said bar, two lower levers, two rods each connecting one arm' of each lower lever with the laterally projecting arm of one of said upper levers, and two rotary cams each operating on the other arm of one of said lower levers.

2. A shearing machine comprising shearing means, abed adapted to support the material to be sheared,andaholddownniechanismhaving a holddown bar whichis a channel shaped in .cross section and movable toward and from the bed, and having an upright lon itudinal web and horiozntal flanges, at t e upper and lower edges ofsaid web and sai flanges being provlded with corresponding the material-to be out,

pairs of upper and lower guide openings, re- I spectively, a plurality of holddown pins each having an enlarged lower part which is guided in a lower guide opening of said lowerupper flange and said pin being provided with an upwardly facing shoulder between its enlarged lower and reduced upper part, a spring surrounding t is reduced part of each pin between the shoulder thereof. and the underside of said upper flange, and a stop screw nut arranged on the upper endof'the reduced part of each pin and adapted to engage the upper side of said upper flange for limiting the downward movement of t pin thereon, the downwardmovement of being stopped before the 3. A shearing machine comprising shearing means, a bed adapted to support the material to be sheared,'and a holddown mechanism having a holddown bar movable to-- ward and from the bed, a holddown pin guided on said bar to slide thereon perpendicular to the plane of said bed, yielding meansoperating to .hold said pin yieldingly in a projectedposition relatively to said bar, and means for actuating said bar comprising measre an intermediate lever turning on a fixed ful=- crum, a link connecting said lever with said and a spring for shifting direction for moving said bed.

bar, a cam for shifting said lever in the direction for moving said bar toward said bed, said lever in the v anism having a holddown bar movable toward and from the bed, a holddown pin guided on said barto slide thereon perpendicular to the plane of said bed, yielding means operating to hold said pin yieldjngly in a projected position relatively to said bar, and means for actuating saidbar comprising an intermediate lever turning on a fixed fulcrum and havinga horizontal upper ar away from said arm projecting laterally from said fulcrum and a vertical lower arm depending from said fulcrum, a link connecting said 'lower arm with said bar, a rotary cam for shifting said lever in the direction for moving said bar toward said bed, an elbow lever having one of its arms, operated upon by said cam, a connecting rod connectin the other; arm of said elbow lever with the orizontal arm of said intermediate lever, a guide rod connected at one end withsaid horizontal arm, a station'- ary guide for the other end of said rod, and a spring surrounding said rod between said guide and said horizontal arm and operatingto turn said intermediate lever in the direction for -moving said bar away from said bed.

FREDERICK E. SGHAUER. 

